An electrostatic recording sheet conventionally comprises a support, a conductive layer provided on the support, and a dielectric layer provided on the conductive layer. The dielectric layer (i.e., an insulating layer) conventionally comprises a soluble binder, e.g., polyvinyl acetate, polystyrene, polyvinyl chloride, polyester, polymethacrylates, or polyvinylidene chloride. Fine particles are dispersed into such a binder for the purposes of making improvements in discharge-in-air characteristics and writing facility. As these particles, inorganic fillers such as silica, clay, alumina or the like have so far been used, as described in Japanese Patent Publication No. 33709/81 (corresponding to U.S. Pat. Nos. 3,711,859 and 3,657,005).
However, an electrostatic recording sheet which contains such inorganic fillers in the dielectric layer, though acquires improved writing facility, suffers form want of moisture resistance. Namely, when recording is carried out in an atmosphere of high humidity, the density of the image obtained is low, or there is a blur on the image obtained. In regions where humidity varies greatly throughout the year, a recording sheet poor in moisture resistance is deficient in respect to practical use. Such being the case, an electrostatic recording sheet with stable recording characteristics regardless of any change in humidity is most desirable.
In addition, electrostatic recording has found increased application lately in the fields of IC (Integrated Circuit) and LSIC (Large-Scale Integrated Circuit). Consequently, greater transparency and dimensional stability are demanded, and the use of a plastic film instead of paper as the support has come to be required. When conventional inorganic pigments or the like are used as the fine particles, haze of the recording sheet is high because of their braod size distribution and low transparency. As a result, the recording sheet is not sufficient in respect to transparency. Since the check of drawings in the field of IC and LSIC is carried out by superimposing three of four films on one anther, high haze is all the more undesirable.
As described above, conventional electrostatic recording sheets in which inorganic fillers are used have problems in respect to moisture resistance and transparency.